Photos of Grumman Windstream 25
Grumman, a famous name in aviation, was active in a number of markets in the 1970s. (They also built aluminum bodies for utility vehicles in the 1970s–and possibly into the 1980s.)
So it wasn’t unexpected that when the US government’s research establishment turned its attention to wind energy that they sought development contracts from the military aerospace industry. I’ve written about why this choice was disastrously unsuccessful in my book Wind Energy Comes of Age.
Grumman at least attempted to commercialize their project, the Grumman Windstream. I remember setting through several presentations in the 1970s from Grumman engineers—working under contracts to the US government—that explained how they experimented with the design and how they planned to manufacture the product. (They planned to put the wind turbine frame on small carts and push the carts between work stands in the plant. Apparently this was the way they built some aircraft components for the military.)
If in one of the photos the hub looks suspiciously like the variable pitch hub from something like a DC3 aircraft—that’s because it was. Later versions may have used a different hub, but that’s what struck me at the time—and that’s what I remember.
Grumman developed two versions: one 25 feet in diameter (7.6 meters) developed in 1977, another 32 feet in diameter (9.8 meters) developed in 1979. Both were rated at 15 kW at 25 mph (11 m/s).
For many years NREL used prototypes of the Grumman turbines for visualization of aerodynamic flow through the rotor and pressure changes in the windstream.